Glycyrrhizin is a major effective component of licorice, and is known to have many actions such as anti-allergic action, anti-inflammatory action, antiviral action and steroid-like action, and it is important as a medicine for treating chronic hepatic diseases. When glycyrrhizin is administered intravenously as an injection, the therapeutic action appears significantly. However, when it is orally administered, the therapeutic action is not clearly shown because of its poor absorption via digestive tracts.
Further, when glycyrrhizin is orally administered, it is hydrolyzed by enterobacteria present on the digestive mucosae to release its sugar moiety, and thus absorbed as glycyrrhetic acid, but the pharmaceutical activity of glycyrrhetic acid against hepatitis is considerably lower than that of glycyrrhizin.
To improve the bioavailability of glycyrrhizin, intra-rectal administration thereof in the form of suppositories has been proposed (JP-A 1-294619, JP-A 3-2122 and JP-A 3-123731).
For improving the absorption thereof via digestive tracts, an oral preparation blended with a fatty acid glyceride and coated with an enteric emulsion or a complex lipid mixture (JP-A 6-192107) have also been proposed. However, these conventional suppositories and oral preparations could not achieve blood glycyrrhizin concentrations enough to demonstrate the efficacy thereof.
Administration thereof by an injection not only gives a sharp pain to the patient but also has to be performed only by a doctor for each administration. Accordingly, administration thereof by an injection into the patient particularly having a chronic disease gives considerable mental and physical pains to the patient.
Accordingly, the object of this invention is to provide a glycyrrhizin preparation which can be administered without being performed by a doctor and giving sharp pain to humans and animals in the form of oral preparations or suppositories in place of injections.